Reassuring the caller that they contacted the correct number or reached the person they intended helps reduce the number of hang-ups and wasted messages you’ll receive. Here are a few notes on how to leave the best greeting possible, along with some voicemail message examples you can use in your own company!
If the mailbox is NOT setup, the fixed system message, "I'm sorry, the person you're trying to reach is unavailable at this time" plays instead of the personal greeting and the mailbox number plays instead of the mailbox name.

When your small business is closed, ensure that your callers know that! If appropriate, you might want to reiterate your business hours to manage callback expectations.
Users often don’t invest enough time into their messages, resulting in incomplete, unprofessional, or otherwise under-whelming greetings. Sure, crafting a greeting doesn’t sound all that complicated; however, there are a number of pitfalls users can fall into—i.e. informality, terseness, sincerity, lack of direction, and more. While none of these sound too catastrophic, they are often interrelated. As such, they tend to worsen any problem. For example, humor can cause informality, worsen ambiguity, and weaken sincerity. That being said, users should strive to avoid ALL these pitfalls.